Tape carrier package and method of fabricating the same

ABSTRACT

A tape carrier package with a widow that is capable of confirming an alignment extent between the tape carrier package and a print wiring board in bonding the tape carrier package mounted with an integrated circuit on the liquid crystal panel and the print wiring board. In the package, the integrated circuit is mounted onto a base film. Input pads are connected to the integrated circuit and formed on the base film. Dummy pads are formed at the left and right side thereof not to be connected to the integrated circuit. Windows are provided by opening the base film adjacent to the dummy pads to expose at least two of said dummy pads.

This Application is a Divisional Application of U.S. application Ser.No. 09/585,439, filed on Jun. 2, 2000, now U.S. Pat. No. 6,559,549.

BACKGROUND OF THE INVENTION

This application claims benefit of Korean patent application numberP2000-0866, filed Feb. 23, 2000, which is hereby incorporated byreference for all purposes as if fully set forth herein.

1. Field of the Invention

This invention relates to a tape carrier package for mounting anintegrated circuit and a liquid crystal display containing the same, andmore particularly to a tape carrier package with a window through whichan alignment between the tape carrier package and a printed wiring boardcan be confirmed with the naked eye.

2. Description of the Related Art

Generally, an active matrix liquid crystal display uses thin filmtransistors (TFTs) as switching devices to display a natural-lookingmoving picture. Since such a liquid crystal display device can be madeinto a smaller-size device than a cathode ray tube, it is commerciallyviable for use as a monitor such as a portable television or a lap-toppersonal computer or other consumer device.

The active matrix liquid crystal display displays a picturecorresponding to video signals such as television signals on a pixel (orpicture element) matrix having pixels arranged at each intersectionbetween gate lines and data lines. Each pixel includes a liquid crystalcell for controlling a transmitted light quantity in accordance with avoltage level of a data signal from a data line. A TFT (thin filmtransistor) is installed at an intersection between a gate line and adata line to switch a data signal to be transferred to the liquidcrystal cell in response to a scanning signal (i.e., a gate pulse) fromthe gate line.

Such a liquid crystal display requires a number of integrated circuits(ICs) connected to the data lines and the gate lines to apply datasignals and scanning signals to the data lines and the gate lines,respectively. The ICs are installed between the printed wiring board(PWB) and the liquid crystal panel to apply signals supplied from thePWB to the data lines and the gate lines. IC mounting methods includechip on board, hereinafter referred to as “COB”, tape automated bonding,hereinafter referred to as “TAB”, and chip on glass, hereinafterreferred to as “COG”. (Other methods are also possible). The COB systemis mainly used for a monochromatic liquid crystal display having a pixelpitch of more than 300 μm. As shown in FIG. 1, in this COB system, ICs 8are mounted on a PWB 6 and a heat-seal connector 10 connects the PWB 6and a glass substrate 3 in a liquid crystal panel 2. In this case, aback light unit 4 used as a light source is provided between the liquidcrystal panel 2 and the PWB 6. As shown in FIG. 2, in the TAB system,ICs 14 are mounted on a tape carrier package (TCP) 12. The TCP 12 isconnected between the PWB 6 and the liquid crystal panel 3. As shown inFIG. 3, in the COG system, an IC chip 20 is directly mounted on a glasssubstrate 17 in a liquid crystal panel 16.

The above-mentioned TAB IC mounting method has been widely employedbecause it can widen an effective area of the panel and has a relativelysimple mounting process.

As shown in FIG. 4, the TCP 12 employed in the TAB system includes abase film 22 on which is mounted an IC 14. The base film 22 is alsoprovided with input and output pads 24 and 26 connected to input andoutput pins of the IC 14. The input and output pads 24 and 26 are fixedwith the base film 22 by an adhesive layer 16 coated on the rear surfaceof the base film 22. The input and output pads 24 and 26 have atwo-layer structure in which copper(Cu) is plated with tin(Sn) forpreventing oxidation. As shown in FIG. 5A, the input pads 24 of the basefilm 22 are connected, via an anisotropic conductive film (ACF) 28, topads 32 on a PWB 34. Likewise, the output pads 26 of the base film 22are connected, via the ACF 30, to data/gate pads on the liquid crystalpanel 2.

FIG. 5A and FIG. 5B illustrate a process of adhering the TCP to the PWBwith the ACF 28. The input pads 24 are adhered to the bare film 22 by abonding layer 16 coated on the base film 22. Conductive particles arecoated on the ACF 28. The TCP 12 and the PWB 34 are adhered to eachother by applying a certain pressure at a desired temperature after theACF 28 has been coated. As shown in FIG. 5B, the conductive particles 30coated on the ACF 28 are connected between the input pads 24 and awiring 32 of the PWB 34 after the adhesion of the TCP 12 to the PWB 34to form a current path.

Because the base film 22 has a low light transmissivity which adhered tothe PWB, it is impossible to confirm an alignment state between theinput pads and the wiring of the PWB. Accordingly, significantly badalignments may be produced in the process of adhering the TCP to thePWB. Also, since the liquid crystal panel made from a glass transmitslight even after the adhesion of the TCP to the PWB, alignment can beconfirmed using a microscope; whereas, since the PWB does not transmitlight, alignment cannot be confirmed using a microscope. Thus, a stronglight is irradiated onto the base film to determine an alignment extentby a light reflected from the input pads. However, this method iscomplicated and unable to accurately determine an alignment. Also, sucha method is time consuming.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a tapecarrier package with a window for confirming an alignment extent withthe naked eye and a liquid crystal display device containing thepackage, and an adhering method thereof.

In order to achieve these and other objects of the invention, a tapecarrier package according to one aspect of the present inventionincludes a base film; an integrated circuit mounted on the base film;input pads connected to the integrated circuit to be formed on the basefilm; dummy pads formed at the side end of the input pads; and windowsprovided by removing the base film adjacent to the dummy pads into adesired size to expose at least two of said dummy pads.

A liquid crystal display device according to another aspect of thepresent invention comprises a liquid crystal panel; a printed wiringboard including an output wiring for receiving image signals from theexterior thereof to output them to the liquid crystal panel, and a dummywiring provided at the side ends of the output wiring; and a tapecarrier package including input pads opposed to the output wiring of theprinted wiring board, output pads corresponding to signal pads of theliquid crystal panel, dummy pads opposed to the dummy wiring of theprinted wiring board at the side ends of the input pads, and windowsdefined by opening the base film to expose at least two of said dummypads, said tape carrier package being adhered, via the input pad and thedummy pads, to the print wiring board and, via the output pads, to theliquid crystal panel.

In some embodiments of the invention, dummy pads are included on theprinted wiring board and TCP. The dummy pads are exposed by the windowin the tape carrier package to confirm alignment of the tape carrierpackage to the PWB. In other embodiments, no dummy pads are provided inthe PWB/TCP. In these embodiments, only a portion of the signal pads areexposed by the window. Some or all of the pads on the TCP/PWB may belengthened to compensate for portions exposed by the window. Of course,this arrangement can also be used even when dummy pads are present.

A method of jointly adhering a tape carrier package of a liquid crystaldisplay device according to still another aspect of the presentinvention includes the steps of adhering input pads and dummy pads ofthe tape carrier package to a wiring of a printed wiring board tocorrespond to each other with an isotropic conductive film therebetween;and confirming an alignment of the dummy pads to the print wiring boardwith the aid of the windows.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects of the invention will be apparent from thefollowing detailed description of preferred embodiments of the presentinvention with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view showing an integrated circuit mounting methodemploying the conventional chip on board system;

FIG. 2 is a sectional view showing an integrated circuit mounting methodemploying the conventional tape automated bonding system;

FIG. 3 is a sectional view showing a liquid crystal display deviceemploying the conventional chip on glass system;

FIG. 4 is a detailed perspective view showing the structure of the tapecarrier package in FIG. 2;

FIG. 5A and FIG. 5B are plan views showing a process of adhering thetape carrier package to the printed wiring board shown in FIG. 4;

FIG. 6 is a detailed perspective view showing the configuration of atape carrier package according to the present invention; and

FIG. 7A and FIG. 7B are sectional views showing a process of adheringthe tape carrier package to the printed wiring board shown in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 6, there is shown a tape carrier package (TCP)according to an embodiment of the present invention. The TCP 40 includesa base film 42, ICs 44 mounted on the base film 42, input and outputpads 48 and 50 connected to the input and output pins of the ICs 44 andformed on the base film 42, dummy pads 46 provided at the side end ofthe input pads 48, and windows 54 defined by openings in the base film42 to confirm an alignment of the dummy pads 46. The input and outputpads 48 and 50 have a two-layer structure in which copper(Cu) is platedwith tin(Sn) for preventing oxidation, and are fixed onto the base film42 with a bonding layer. For example, the dummy pads 46 are formed fiveby five at the left and right side of the input pads 48. The windows 54are formed into a square shape by punching the base film 42 providedwith the dummy pads 46. The windows 54 are punched into such a desiredsize that alignment between the first two or three dummy lines 46 can beconfirmed with the naked eye. The dummy pads 46 that are provided withthe window 54 prevent an alien substance from coming into contact withthe input pads 48. As shown in FIG. 7A, the input pads 48 fixed onto thebase film 42 are connected to the signal wiring 64 on the PWB 60 withthe aid of the ACF 56. Likewise, the output pads 50 of the base film 42are connected to data and gate pads on the liquid crystal panel with theaid of the ACF 56.

FIG. 7A and FIG. 7B show a process of adhering the TCP to the PWB.Referring to FIG. 7A and FIG. 7B, there is shown the ACF 56 for adheringthe TCP 40 to the PWB 60. The PWB 60 is provided with the dummy wiring58 corresponding to the dummy pads 46 formed at the TCP 40. The inputpads 48 and the dummy lines 46 of the TCP 40 are provided after thewindows 54 are formed on the base film 42.

Hereinafter, an adhesion process of the liquid crystal using the tapecarrier package will be described in detail. After the ACF 56 has beencoated on the PWB 60, the TCP 40 is jointly adhered to the PWB 60 asshown in FIG. 7B by applying a certain pressure thereto at a desiredtemperature. Since the conductive particles 62 contained in the ACF 56between the input pads 48 and the dummy pads 46 of the TCP 40 andbetween the wiring 64 and the dummy wiring 58 of the PWB 60 have anincreased density caused by the pressure, they connect the input pads 48to the wiring 64 of the PWB 60 electrically. In this case, an alignmentof the dummy pads 46 and the dummy wiring 58 is confirmed by means ofthe windows to check alignment errors.

As described above, according to the present invention, a desired sizeof windows are formed on the base film to confirm an alignment statebetween the tape carrier package and the print wiring board.Accordingly, the time required to check for misalignment can bedramatically shortened.

Although the present invention has been described in connection with theembodiments shown in the drawings described above, it should beunderstood by a person of ordinary skill in the art that the inventionis not limited to these embodiments, but rather that various changes ormodifications thereof are possible without departing from the spirit ofthe invention. Accordingly, the scope of the invention shall bedetermined only by the appended claims and their equivalents.

1. A method of jointly adhering a print wiring board to a tape carrierpackage including input pads on a base film, at least one dummy padformed at a side of the input pads, and a window for exposing a portionof the at least one dummy pad, said method comprising the steps of:adhering the input pads and the at least one dummy pad of the tapecarrier package to a wiring of the print wiring board to correspond toeach other with an isotropic conductive film therebetween; andconfirming an alignment of the at least one dummy pad to a dummy pad onthe printed wiring board with the aid of the window.
 2. A methodaccording to claim 1, further including an integrated circuit attachedto said base film.
 3. A method according to claim 2, wherein saidintegrated circuit is attached to said second side.
 4. A methodaccording to claim 2, wherein said integrated circuit is attached with abonding layer.
 5. A method according to claim 1, wherein the base filmincludes: a first edge, a second edge, a front, a rear, a first side,and a second side, said base film further having a first window disposedalong said first edge near said front and a second window disposed alongsaid first edge near said rear.
 6. A method according to claim 5,further comprising: forming an electrically conductive pattern on saidfirst side of said base film, said electrically conductive patternhaving a plurality of first edge pads that extend inward from said firstedge, wherein said plurality of first edge pads are for carryingelectrical signals to and from external circuitry; forming a forwarddummy pad that spans said first window; and forming a rear dummy padthat spans said second window.
 7. A method according to claim 6, furtherincluding forming at least one additional dummy pad on said base filmbetween said plurality of first edge pads and either the first window orthe second window.
 8. A method according to claim 6, wherein saidforward dummy pad and said rear dummy pad are uniformly spaced relativeto the first edge pads.
 9. A method according to claim 6, wherein saidconductive pattern is a two layer structure that includes a copper layerand an oxidation prevention layer.
 10. A method according to claim 6,wherein said forward and said rear dummy leads do not carry electricalsignals.
 11. A method according to claim 6, wherein said first windowand said second window are substantially square.
 12. A method accordingto claim 1, wherein the print wiring board further comprises forming aplurality of linearly aligned circuit board pads for carrying electricalsignals, said circuit board further having a plurality of dummyconnectors on both sides of said plurality of circuit board pads; andthe base film further comprises a first edge, a second edge, a front, arear, a first side, and a second side, said base film further having afirst window disposed along said first edge near said front and a secondwindow disposed along said first edge near said rear.
 13. A methodaccording to claim 12, further comprising: forming an electricallyconductive pattern on said first side of said base film, saidelectrically conductive pattern having a plurality of first edge padsthat extend inward from said first edge and that align with andelectrically connect to said circuit board pads; forming a forward dummypad that spans said first window and that aligns with a dummy connectoron said circuit board; forming a rear dummy pad that spans said secondwindow and that aligns with a dummy connector on said circuit board; andforming an integrated circuit on said base film.
 14. A method accordingto claim 13, wherein said integrated circuit is attached to said secondside.
 15. A method according to claim 13, wherein said integratedcircuit is attached with a bonding layer.
 16. A method according toclaim 13, further including forming at least one additional dummy pad onsaid base film between said plurality of first edge pads and either thefirst window or the second window.
 17. A method according to claim 13,wherein said forward dummy pad and said two rear dummy pad are uniformlyspaced relative to the first edge pads.
 18. A method according to claim13, wherein said plurality of first edge pads and said plurality ofcircuit board pads are electrically connected by an anisotropicconductive film.
 19. A method according to claim 13, wherein saidforward and rear dummy leads do not carry electrical signals.
 20. Amethod according to claim 13, wherein said first window and said secondwindow are substantially square.
 21. A method according to claim 1,further comprising: forming a liquid crystal panel for producing animage in response to output signals applied to a plurality of liquidcrystal pads.
 22. A method according to claim 21, wherein the printwiring board further comprises forming a plurality of circuit board padsfor carrying input signals, said circuit board further having aplurality of dummy connectors on both sides of said plurality of circuitboard pads; and the base film further comprises a first edge, a secondedge, a front, a rear, a first side, and a second side, said base filmfurther includes a first window disposed along said first edge near saidfront and a second window disposed along said first edge near said rear.23. A method according to claim 22, further comprising: forming anelectrically conductive pattern on said first side of said base film,said electrically conductive pattern having a plurality of input padsthat extend inward from said first edge and that align with andelectrically connect to said plurality of circuit board pads, saidelectrically conductive pattern further having a plurality of outputpads that align with and electrically connect to said plurality ofliquid crystal pads; forming a forward dummy pad that spans said firstwindow and that aligns with a dummy connector on said circuit board;forming a rear dummy pad that spans said second window and that alignswith a dummy connector on said circuit board; and forming an integratedcircuit on said base film, said integrated circuit for receiving inputsignals from said circuit board via said plurality of input pads, saidintegrated circuit further for converting said input signals to outputsignals, wherein said output signals are applied to said liquid crystalpanel via said plurality of output pads.
 24. A method according to claim23, wherein said integrated circuit is attached to said second side. 25.A method according to claim 23, wherein said integrated circuit isattached with a bonding layer.
 26. A method according to claim 23,further including forming at least one additional dummy pad on said basefilm between said plurality of first edge pads and either the firstwindow or the second window.
 27. A method according to claim 23, whereinsaid two forward dummy pads and said two rear dummy pads are uniformlyspaced along the first edge.
 28. A method according to claim 23, whereinsaid plurality of first edge pads and said plurality of circuit boardpads are electrically connected by an anisotropic conductive film.
 29. Amethod according to claim 23, wherein said forward and said rear dummyleads do not carry electrical signals.
 30. A method according to claim23, wherein said first window and said second window are substantiallysquare.